For evidence to be admissible in a criminal prosecution it generally must have been obtained legally—with a search warrant, or based on an exception to the search warrant requirement, such as consent to search—and be relevant and reliable.
In Alabama, as in other states, evidence must be obtained legally to be admissible in a criminal prosecution. This means that law enforcement officers typically need to have a valid search warrant before conducting a search and seizing evidence. However, there are exceptions to this requirement, such as when an individual gives consent to a search, when evidence is in plain view, during a search incident to a lawful arrest, or in emergency situations where there is a risk of evidence being destroyed or someone's safety is at risk (exigent circumstances). Additionally, the evidence must be relevant to the case, meaning it must have some bearing on the crime being prosecuted, and it must be reliable, indicating that it is trustworthy and has integrity. If evidence is obtained in violation of these principles, it may be subject to suppression through a motion to suppress, meaning it cannot be used against the defendant in court. This is in line with the Fourth Amendment of the U.S. Constitution, which protects against unreasonable searches and seizures, and is enforced through the exclusionary rule.